Relativity Ch.37 Test Bank

Chapter: Chapter 37

Learning Objectives

LO 37.1.0 Solve problems related to simultaneity and time dilation.

LO 37.1.1 Identify the two postulates of (special) relativity and the type of frames to which they apply.

LO 37.1.2 Identify the speed of light as the ultimate speed and give its approximate value.

LO 37.1.3 Explain how the space and time coordinates of an event can be measured with a three dimensional array of clocks and measuring rods and how that eliminates the need of a signal’s travel time to an observer.

LO 37.1.4 Identify that the relativity of space and time has to do with transferring measurements between two inertial frames with relative motion but we still use classical kinematics and Newtonian mechanics within a frame.

LO 37.1.5 Identify that for reference frames with relative motion, simultaneous events in one of the frames will generally not be simultaneous in the other frame.

LO 37.1.6 Explain what is meant by the entanglement of the spatial and temporal separations between two events.

LO 37.1.7 Identify the conditions in which a temporal separation of two events is a proper time.

LO 37.1.8 Identify that if the temporal separation of two events is a proper time as measured in one frame, that separation is greater (dilated) as measured in another frame.

LO 37.1.9 Apply the relationship between proper time Δt₀, dilated time Δt, and the relative speed v between two frames.

LO 37.1.10 Apply the relationships between the relative speed v, speed parameter β, and the Lorentz factor γ.

LO 37.2.0 Solve problems related to the relativity of length.

LO 37.2.1 Identify that because spatial and temporal separations are entangled, measurements of the lengths of objects may be different in two frames with relative motion.

LO 37.2.2 Identify the condition in which a measured length is a proper length.

LO 37.2.3 Identify that if a length is a proper length as measured in one frame, the length is less (contracted) as measured in another frame that is in relative motion parallel to the length.

LO 37.2.4 Apply the relationship between contracted length L, proper length L₀, and the relative speed v between two frames.

LO 37.3.0 Solve problems related to the Lorentz transformations.

LO 37.3.1 For frames with relative motion, apply the Galilean transformation to transform an event’s position from one frame to the other.

LO 37.3.2 Identify that a Galilean transformation is approximately correct for slow relative speeds but the Lorentz transformations are the correct transformations for any physically possible speed.

LO 37.3.3 Apply the Lorentz transformations for the spatial and temporal separations of two events as measured in two frames with a relative speed v.

LO 37.3.4 From the Lorentz transformations, derive the equations for time dilation and length contraction.

LO 37.3.5 From the Lorentz transformations show that if two events are simultaneous but spatially separated in one frame, they cannot be simultaneous in another frame with relative motion.

LO 37.4.0 Solve problems related to the relativity of velocities.

LO 37.4.1 With a sketch, explain the arrangement in which a particle’s velocity is to be measured relative to two frames that have relative motion.

LO 37.4.2 Apply the relationship for a relativistic velocity transformation between two frames with relative motion.

LO 37.5.0 Solve problems related to Doppler effect for light.

LO 37.5.1 Identify that the frequency of light as measured in a frame attached to the light source (the rest frame) is the proper frequency.

LO 37.5.2 For source–detector separations increasing and decreasing, identify whether the detected frequency is shifted up or down from the proper frequency, identify that the shift increases with an increase in relative speed, and apply the terms blue shift and red shift.

LO 37.5.3 Identify radial speed.

LO 37.5.4 For source–detector separations increasing and decreasing, apply the relationships between proper frequency f₀, detected frequency f, and radial speed v.

LO 37.5.5 Convert between equations for frequency shift and wavelength shift.

LO 37.5.6 When a radial speed is much less than light speed, apply the approximation relating wavelength shift Δλ, proper wavelength λ₀, and radial speed v.

LO 37.5.7 Identify that for light (not sound) there is a shift in the frequency even when the velocity of the source is perpendicular to the line between the source and the detector, an effect due to time dilation.

LO 37.5.8 Apply the relationship for the transverse Doppler effect by relating detected frequency f, proper frequency f₀, and relative speed v.

LO 37.6.0 Solve problems related to momentum and energy.

LO 37.6.1 Identify that the classical expressions for momentum and kinetic energy are approximately correct for slow speeds whereas the relativistic expressions are correct for any physically possible speed.

LO 37.6.2 Apply the relationship between momentum, mass, and relative speed.

LO 37.6.3 Identify that an object has a mass energy (or rest energy) associated with its mass.

LO 37.6.4 Apply the relationships between total energy, rest energy, kinetic energy, momentum, mass, speed, the speed parameter and the Lorentz factor.

LO 37.6.5 Sketch a graph of kinetic energy versus the ratio v/c (of speed to light speed) for both classical and relativistic expressions of kinetic energy.

LO 37.6.6 Apply the work–kinetic energy theorem to relate work by an applied force and the resulting change in kinetic energy.

LO 37.6.7 For a reaction, apply the relationship between the Q value and the change in the mass energy.

LO 37.6.8 For a reaction, identify the correlation between the algebraic sign of Q and whether energy is released or absorbed by the reaction.

Multiple Choice

1. Two events occur simultaneously at separated points on the y axis of reference frame S. According to an observer moving in the positive x direction:

A) the event with the greater y coordinate occurs first

B) the event with the greater y coordinate occurs last

C) either event might occur first, depending on the observer's speed

D) the events are simultaneous

E) none of the above

Difficulty: E

Section: 37-1

Learning Objective 37.1.0

2. A train traveling very fast (v = 0.6c) has an engineer (E) at the front, a guard (G) at the rear and an observer (S') exactly half way between them. Both E and G are equipped with yellow signaling lamps. The train passes a station, closely observed by the station master (S). Both E and G use their lamps to send signals. According to both S and S' these signals arrive simultaneously at the instant S' is passing S. According to S':

A) E and G sent their signals simultaneously from different distances

B) G sent his signal before E and from further away

C) G sent his signal before E but was the same distance away

D) E sent his signal before G and from further away

E) none of the above

Difficulty: E

Section: 37-1

Learning Objective 37.1.0

3. A basic postulate of Einstein's theory of relativity is:

A) moving clocks run more slowly than when they are at rest

B) moving rods are shorter than when they are at rest

C) light has both wave and particle properties

D) the laws of physics must be the same for observers moving with uniform velocity relative to each other

E) everything is relative

Difficulty: E

Section: 37-1

Learning Objective 37.1.1

4. The speed of light in vacuum is approximately

A) 186,000 miles per hour

B) 300,000 km per minute

C) one foot per nanosecond

D) 186,000 feet per second

E) 300,000 meters per second

Difficulty: E

Section: 37-1

Learning Objective 37.1.2

5. Two events occur simultaneously on the x axis of reference frame S, one at x = a and the other at x = +a. According to an observer moving in the positive x direction:

A) the event at x = +a occurs first

B) the event at x = a occurs first

C) either event might occur first, depending on the value of a and the observer's speed

D) the events are simultaneous

E) none of the above

Difficulty: E

Section: 37-1

Learning Objective 37.1.5

6. The proper time between two events is measured by clocks at rest in a reference frame in which the two events:

A) occur at the same time

B) occur at the same coordinates

C) are separated by the distance a light signal can travel during the time interval

D) occur on the Earth’s surface

E) none of the above

Difficulty: E

Section: 37-1

Learning Objective 37.1.7

7. The spaceship U.S.S. Enterprise, traveling through the galaxy, sends out a smaller explorer craft that travels to a nearby planet and signals its findings back. The proper time for the trip to the planet is measured by clocks:

A) on board the Enterprise

B) on board the explorer craft

C) on Earth

D) at the center of the galaxy

E) none of the above

Difficulty: E

Section: 37-1

Learning Objective 37.1.7

8. As we watch, a spaceship passes us in time t. The crew of the spaceship measures the passage time and finds it to be t'. Which of the following statements is true?

A) t is the proper time for the passage and it is smaller than t'

B) t is the proper time for the passage and it is greater than t'

C) t' is the proper time for the passage and it is smaller than t

D) t' is the proper time for the passage and it is greater than t

E) None of the above statements are true.

Difficulty: E

Section: 37-1

Learning Objective 37.1.8

9. A millionairess was told in 1992 that she had exactly 15 years to live. However, if she immediately takes off, travels away from the Earth at 0.8 c and then returns at the same speed, the last New Year's Day the doctors expect her to celebrate is:

A) 2001

B) 2003

C) 2007

D) 2017

E) 2033

Difficulty: E

Section: 37-1

Learning Objective 37.1.9

10. An observer notices that a moving clock runs slow by a factor of exactly 10. The speed of the clock is:

A) 0.0100c

B) 0.100c

C) 0.900c

D) 0.990c

E) 0.995c

Difficulty: M

Section: 37-1

Learning Objective 37.1.9

11. A meson when at rest decays 2 s after it is created. If moving in the laboratory at 0.99c, its lifetime according to laboratory clocks would be:

A) the same

B) 0.28 s

C) 4.6 s

D) 14 s

E) none of these

Difficulty: M

Section: 37-1

Learning Objective 37.1.9

12. Pi mesons at rest have a half-life of T. If a beam of pi mesons is traveling at a speed of

v = c, the distance in which the intensity of the beam is halved is:

A) cT(1 – ²)^–1/2

B) cT[(1 + )/(1 – )]^1/2

C) vT

D) (1 – ²)^1/2vT

E) none of the above

Difficulty: M

Section: 37-1

Learning Objective 37.1.9

13. A meson moving through a laboratory of length x at a speed v decays after a lifetime T as measured by an observer at rest in the laboratory. If the meson were at rest in the laboratory its lifetime would be:

A) T(1 – v/c)

B) T(1 – v/c)^–1

C) T(1 – v²/c²)^–1/2

D) T(1 – v²/c²)^1/2

E) (T – vx/c²)(1 – v²/c²)^–1/2

Difficulty: M

Section: 37-1

Learning Objective 37.1.9

14. A meter stick moves sideways (that is, in a direction perpendicular to its length) at 0.95c. According to measurements taken in the laboratory, its length is:

A) 0 m

B) 0.098 m

C) 0.31 m

D) 1.0 m

E) 3.2 m

Difficulty: E

Section: 37-2

Learning Objective 37.2.0

15. A consequence of Einstein's theory of relativity is:

A) moving clocks appear to run more slowly than when they are at rest

B) moving rods appear longer than when they are at rest

C) light has both wave and particle properties

D) the laws of physics must appear the same to all observers moving with uniform velocity relative to each other

E) everything is relative

Difficulty: E

Section: 37-2

Learning Objective 37.2.0

16. According to the theory of relativity:

A) moving clocks run fast

B) energy is not conserved in high speed collisions

C) the speed of light must be measured relative to the ether

D) momentum is not conserved in high speed collisions

E) none of the above

Difficulty: E

Section: 37-2

Learning Objective 37.2.0

17. A measurement of the length of an object that is moving relative to the laboratory consists of noting the coordinates of the front and back:

A) at different times according to clocks at rest in the laboratory

B) at the same time according to clocks that move with the object

C) at the same time according to clocks at rest in the laboratory

D) at the same time according to clocks at rest with respect to the fixed stars

E) none of the above

Difficulty: E

Section: 37-2

Learning Objective 37.2.2

18. A consequence of Einstein's theory of relativity is:

A) moving clocks appear to run faster than when they are at rest

B) moving rods appear shorter than when they are at rest

C) light has both wave and particle properties

D) the laws of physics must appear the same to all observers moving with uniform velocity relative to each other

E) everything is relative

Difficulty: E

Section: 37-2

Learning Objective 37.2.3

19. A meter stick moves in the direction of its length through a laboratory. According to measurements taken in the laboratory, its length is 0.31 m. The speed of the meter stick relative to the laboratory is:

A) 0.096c

B) 0.31c

C) 0.69c

D) 0.83c

E) 0.95c

Difficulty: M

Section: 37-2

Learning Objective 37.2.4

20. A rocket ship of rest length 100 m is moving at speed 0.8c past a timing device which records the time interval between the passage of the front and back ends of the ship. This time interval is:

A) 0.20 s

B) 0.25 s

C) 0.33 s

D) 0.52 s

E) 0.69 s

Difficulty: M

Section: 37-2

Learning Objective 37.2.4

21. A certain automobile is 6.0 m long if at rest. If it is measured to be 4.8 m long while moving, its speed is:

A) 0.1c

B) 0.3c

C) 0.6c

D) 0.8c

E) > 0.95c

Difficulty: M

Section: 37-2

Learning Objective 37.2.4

22. A clock is moving along the x axis at 0.6c. It reads zero as it passes the origin (x = 0). When it passes the x = 180 m mark on the x axis the clock reads:

A) 0.60 s

B) 0.80 s

C) 1.00 s

D) 1.25 s

E) 1.67 s

Difficulty: M

Section: 37-2

Learning Objective 37.2.4

23. Two events occur on the x axis separated in time by t and in space by x. A reference frame, traveling at less than the speed of light, in which the two events occur at the same time:

A) exists no matter what the values of x and t

B) exists only if x/t < c

C) exists only if x/t > c

D) exists only if x/t = c

E) does not exist under any condition

Difficulty: M

Section: 37-3

Learning Objective 37.3.0

24. Two events occur on the x axis separated in time by t and in space by x. A reference frame, traveling at less than the speed of light, in which the two events occur at the same coordinate:

A) exists no matter what the values of x and t

B) exists only if x/t < c

C) exists only if x/t > c

D) exists only if x/t = c

E) does not exist under any condition

Difficulty: M

Section: 37-3

Learning Objective 37.3.0

25. Which statement is correct?

A) Galilean transformations are correct at any relative speed, but Lorentz transformations are only approximately correct for relative speeds near the speed of light.

B) Lorentz transformations are correct at any relative speed, but Galilean transformations are only approximately correct for relative speeds near the speed of light.

C) Galilean transformations are correct at any relative speed, but Lorentz transformations are only approximately correct for relative speeds that are small compared to the speed of light.

D) Lorentz transformations are correct at any relative speed, but Galilean transformations are only approximately correct for relative speeds that are small compared to the speed of light.

E) Galilean transformations are only approximately correct for relative speeds that are small compared to the speed of light, and Lorentz transformations are only approximately correct for relative speeds near the speed of light.

Difficulty: E

Section: 37-3

Learning Objective 37.3.2

26. The length of a meter stick moving at 0.95c in the direction of its length with respect to the laboratory is measured by simultaneously marking its ends on an axis which is stationary in the laboratory. As measured by clocks moving with the stick, the time interval between the making of the back mark and the making of the front mark is:

A) 0 s

B) 1.1  10^–9 s

C) 3.2  10^–9 s

D) 3.5  10^–9 s

E) 1.1  10^–8 s

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

27. Two events occur 100 m apart with an intervening time interval of 0.60 s. The speed of a reference frame in which they occur at the same coordinate is:

A) 0 c

B) 0.25c

C) 0.56c

D) 1.1c

E) 1.8c

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

28. Two independent events occur 100 m apart with an intervening time interval of 0.42 s. The proper time between the events is:

A) 0 s

B) 0.16 s

C) 0.26 s

D) 0.42 s

E) 0.69 s

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

29. Two events occur 100 m apart with an intervening time interval of 0.37 s. The speed of a clock that measures the proper time between the events is:

A) 0 c

B) 0.45c

C) 0.56c

D) 0.90c

E) 1.8c

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

30. A rocket traveling with constant velocity makes an 8.4  10¹⁵ m trip in 1 year. The proper time between events which mark the beginning and end of the trip is:

A) 0.21 years

B) 0.46 years

C) 1.0 years

D) 2.2 years

E) 4.7 years

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

31. As a rocket ship moves by at 0.95c a mark is made on a stationary axis at the front end of the rocket and 9.0  10^–8 s later a mark is made on the axis at the back end. The marks are 100 m apart. The rest length of the rocket is:

A) 31 m

B) 78 m

C) 100 m

D) 240 m

E) 320 m

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

32. Relative to reference frame 1, reference frame 2 moves with speed v in the negative x direction. When the origins of the two frames coincide the clocks in both frames are set to zero. An event occurs at coordinate x₁ and time t₁ as measured in reference frame 1 and at coordinate x₂ and time t₂ as measured in frame 2. If , then the coordinates and times of the event are related by:

A) x₂ = [x₁ – vt₁] and t₂ = [t₁ – vx₁ / c²]

B) x₂ = [x₁ – vt₁] and t₂ = [t₁ + vx₁ / c²]

C) x₂ = [x₁ + vt₁] and t₂ = [t₁ – vx₁ / c²]

D) x₂ = [x₁ + vt₁] and t₂ = [t₁ + vx₁ / c²]

E) none of the above are correct

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

33. An event occurs at x = 500 m, t = 0.90 s in one frame of reference. Another frame is moving at 0.90c in the positive x direction. The origins coincide at t = 0 and clocks in the second frame are zeroed when the origins coincide. The coordinate and time of the event in the second frame is:

A) 500 m, 0.90 s

B) 1700 m, 5.5 s

C) 740 m, 2.4 s

D) 260 m, –0.60 s

E) 590 m, –1.4 s

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

34. An event occurs at x = 500 m, t = 0.90 s in one frame of reference. Another frame is moving at 0.90c in the negative x direction. The origins coincide at t = 0 and clocks in the second frame are zeroed when the origins coincide. The coordinate and time of the event in the second frame is:

A) 500 m, 0.90 s

B) 1700 m, 5.5 s

C) 740 m, 2.4 s

D) 260 m, –0.60 s

E) 590 m, –1.4 s

Difficulty: M

Section: 37-3

Learning Objective 37.3.3

35. Two flashes of light occur simultaneously at t = 0 in reference frame S, one at x = 0 and the other at x = 600 m. They are observed in reference frame S', which is moving at 0.95c in the positive x direction. The origins of the two frames coincide at t = 0 and the clocks of S' are zeroed when the origins coincide. In S' the coordinate where the leading edges of the two light flashes meet and the time when they meet are:

A) 300 m, 1.0 s

B) 15 m, 0.050 s

C) 585 m, 1.95 s

D) 48 m, 0.16 s

E) 1900 m, 0.16 s

Difficulty: H

Section: 37-3

Learning Objective 37.3.3

36. Spaceship A, traveling past us at 0.7c, sends a message capsule to spaceship B, which is in front of A and is traveling in the same direction as A at 0.8c relative to us. The capsule travels at 0.95c relative to us. A clock that measures the proper time between the sending and receiving of the capsule travels:

A) in the same direction as the spaceships at 0.7c relative to us

B) in the opposite direction from the spaceships at 0.7c relative to us

C) in the same direction as the spaceships at 0.8c relative to us

D) in the same direction as the spaceships at 0.95c relative to us

E) in the opposite direction from the spaceships at 0.95c relative to us

Difficulty: E

Section: 37-4

Learning Objective 37.4.2

37. Frame S' moves in the positive x direction at 0.6c with respect to frame S. A particle moves in the positive x direction at 0.4c as measured by an observer in S'. The speed of the particle as measured by an observer in S is:

A) c/5

B) 5c/19

C) 8c/25

D) 25c/31

E) c

Difficulty: M

Section: 37-4

Learning Objective 37.4.2

38. Star S1 is moving away from us at a speed of 0.8c. Star S2 is moving away from us in the opposite direction at a speed of 0.5c. The speed of S1 as measured by an observer on S2 is:

A) 0.21c

B) 0.50c

C) 0.93c

D) 1.3c

E) 2.2c

Difficulty: M

Section: 37-4

Learning Objective 37.4.2

39. Observer A measures the velocity of a rocket as and a comet as . Here and are parallel and in the direction of the observer's positive x axis. The speed of the comet as measured by an observer on the rocket is:

A) (u – v)/(1 – uv/c²)

B) (u – v)/(1 – v²/c²)

C) (u – v)/(1 – v²/c²)^1/2

D) (u – v)/(1 + uv/c²)

E) (u + v)/(1 – uv/c²)

Difficulty: M

Section: 37-4

Learning Objective 37.4.2

40. Two electrons move in opposite directions at 0.70c as measured in the laboratory. The speed of one electron as measured from the other is:

A) 0.35c

B) 0.70c

C) 0.94c

D) 1.00c

E) 1.40c

Difficulty: M

Section: 37-4

Learning Objective 37.4.2

41. Light from some stars shows an apparent change in frequency because of:

A) interference

B) refraction by layers of air

C) diffraction

D) reflection

E) relative motion

Difficulty: E

Section: 37-5

Learning Objective 37.5.0

A) the detector is moving to the right with a speed that is greater than c/4 relative to S

B) the detector is moving to the right with a speed that is less than c/4 relative to S

C) the detector is moving to the left with a speed that is greater than c/4 relative to S

D) the detector is moving to the left with a speed that is less than c/4 relative to S

E) the detector is not moving

Difficulty: E

Section: 37-5

Learning Objective 37.5.2

43. Light from a stationary spaceship is observed, then the spaceship moves directly away from the observer at high speed. As a result, the light seen by the observer has:

A) a higher frequency and a longer wavelength than before

B) a lower frequency and a shorter wavelength than before

C) a higher frequency and a shorter wavelength than before

D) a lower frequency and a longer wavelength than before

E) the same frequency and wavelength as before

Difficulty: E

Section: 37-5

Learning Objective 37.5.2

44. A train traveling very fast (v = 0.6c) has an engineer (E) at the front, a guard (G) at the rear and a passenger (S') exactly half way between them. Both E and G are equipped with yellow signaling lamps. The train passes a station, closely observed by the station master (S). Both E and G use their lamps to send signals. According to both S and S' these signals arrive simultaneously at the instant S' is passing S. According to S, the signal from E will look ______ and that from G will look _____:

A) red, blue

B) yellow, yellow

C) blue, red

D) blue, blue

E) red, red

Difficulty: E

Section: 37-5

Learning Objective 37.5.2

45. A console lamp in the cabin of a spaceship appears green when the ship and observer are both at rest. When the ship is moving at 0.90c away from Earth, passengers on board see:

A) a dark lamp (the frequency is too high to be seen)

B) a dark lamp (the frequency is too low to be seen)

C) a red lamp

D) a violet lamp

E) a green lamp

Difficulty: M

Section: 37-5

Learning Objective 37.5.4

46. Visible light, with a frequency of 6.0  10¹⁴ Hz, is reflected from a spaceship moving directly away at a speed of 0.90c. The frequency of the reflected waves observed at the source is:

A) 3.2  10¹³ Hz

B) 1.4  10¹⁴ Hz

C) 6.0  10¹⁴ Hz

D) 2.6  10¹⁵ Hz

E) 1.1  10¹⁶ Hz

Difficulty: M

Section: 37-5

Learning Objective 37.5.4

47. How fast should you move away from a 6.0  10¹⁴ Hz light source to observe waves with a frequency of 4.0  10¹⁴ Hz?

A) 0.20c

B) 0.39c

C) 0.45c

D) 0.51c

E) 0.76c

Difficulty: M

Section: 37-5

Learning Objective 37.5.4

48. A spectral line of a certain star is observed to be "red shifted" from a wavelength of 500 nm to a wavelength of 1500 nm. Interpreting this as a Doppler effect, the speed of recession of this star is:

A) 0.33c

B) 0.50c

C) 0.71c

D) 0.80c

E) c

Difficulty: M

Section: 37-5

Learning Objective 37.5.6

49. A source at rest emits light of wavelength 500 nm. When it is moving at 0.90c toward an observer, the observer detects light of wavelength:

A) 26 nm

B) 115 nm

C) 500 nm

D) 2200 nm

E) 9500 nm

Difficulty: M

Section: 37-5

Learning Objective 37.5.6

50. A source at rest emits light of wavelength 500 nm. When it is moving at 0.90c away from an observer, the observer detects light of wavelength:

A) 26 nm

B) 115 nm

C) 500 nm

D) 2200 nm

E) 9500 nm

Difficulty: M

Section: 37-5

Learning Objective 37.5.6

51. A distant star has a transverse speed (perpendicular to our line of sight) of 30,000 km/s with respect to Earth. Its spectrum has an absorption line at a frequency of 5.00 x 10¹⁴ Hz. What is the frequency of that line as observed on Earth?

A) 4.50 x 10¹⁴ Hz

B) 4.90 x 10¹⁴ Hz

C) 4.97 x 10¹⁴ Hz

D) 5.00 x 10¹⁴ Hz

E) 5.04 x 10¹⁴ Hz

Difficulty: M

Section: 37-5

Learning Objective 37.5.8

52. If the mass of a particle is zero its speed must be:

A) c

B) infinite

C) 0

D) any speed less than c

E) any speed greater than c

Difficulty: E

Section: 37-6

Learning Objective 37.6.0

53. According to the theory of relativity:

A) mass is a form of energy

B) moving particles lose mass

C) momentum is not conserved in high speed collisions

D) a rod moving rapidly sideways (perpendicular to its length) is shorter along its length

E) a rod moving rapidly sideways (perpendicular to its length) is longer along its length

Difficulty: E

Section: 37-6

Learning Objective 37.6.0

54. If the kinetic energy of a free particle is much less than its rest energy then its kinetic energy is proportional to:

A) the magnitude of its momentum

B) the square of the magnitude of its momentum

C) the square root of the magnitude of its momentum

D) the reciprocal of the magnitude of its momentum

E) none of the above

Difficulty: M

Section: 37-6

Learning Objective 37.6.1

55. An electron (m = 9.11  10^–31 kg) has a speed of 0.95c. The magnitude of its momentum is:

A) 2.6  10^–22 kg  m/s

B) 2.9  10^–22 kg  m/s

C) 6.0  10^–22 kg  m/s

D) 8.3  10^–22 kg  m/s

E) 8.8  10^–22 kg  m/s

Difficulty: M

Section: 37-6

Learning Objective 37.6.2

56. According to relativity theory a particle of mass m with a momentum of 2mc has a speed of:

A) 4c

B) 2c

C) c

D) 0.89c

E) c/2

Difficulty: M

Section: 37-6

Learning Objective 37.6.2

57. A particle with zero mass and energy E carries momentum:

A) Ec

B) Ec²

C)

D) E/c

E) E/c²

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

58. If the kinetic energy of a free particle is much greater than its rest energy then its kinetic energy is proportional to:

A) the magnitude of its momentum

B) the square of the magnitude of its momentum

C) the square root of the magnitude of its momentum

D) the reciprocal of the magnitude of its momentum

E) none of the above

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

59. A particle with rest mass m moves with speed 0.6c. Its kinetic energy is:

A) 0.18mc²

B) 0.22mc²

C) 0.25mc²

D) mc²

E) 1.25mc²

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

60. An electron is moving at 0.6c. If we calculate its kinetic energy using (1/2)mv², we get a result which is:

A) just right

B) just half enough

C) twice the correct value

D) about 1% too low

E) about 28% too low

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

61. The velocity of an electron is changed from c/2 in the –x direction to c/2 in the +x direction. As a result, its kinetic energy changes by:

A) 2mc²

B) mc²

C) mc²

D) 0.5mc²

E) 0

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

62. An electron (m = 9.11  10^–31 kg) has a speed of 0.95c. Its kinetic energy is:

A) 8.2  10^–14 J

B) 1.8  10^–13 J

C) 2.0  10^–13 J

D) 2.2  10^–13 J

E) 2.6  10^–13 J

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

63. The mass of a particle is m. In order for its total energy to be twice its rest energy, its momentum must be:

A) mc/2

B) mc/

C) mc

D) mc

E) 2mc

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

64. If the kinetic energy of a particle is equal to its rest energy then its speed must be:

A) 0.25c

B) 0.50c

C) 0.87c

D) c

E) unknown unless its mass is given

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

65. The magnitude of the momentum of a particle can never exceed:

A) mc, where m is its mass

B) E/c, where E is its energy

C) K/c, where K is its kinetic energy

D) none of the above, but there is an upper limit

E) none of the above; there is no upper limit

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

66. An electron (m = 9.11  10^–31 kg) has a momentum of 1.3  10^–21 kg m/s. Its kinetic energy is:

A) 6.3  10^–14 J

B) 8.2  10^–14 J

C) 1.5  10^–13 J

D) 3.2  10^–13 J

E) 4.0  10^–13 J

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

67. A certain particle has a kinetic energy of 3.2  10^–10 J and a momentum of 1.7  10^–18 kg  m/s. Its mass is:

A) 9.1  10^–31 kg

B) 2.7  10^–27 kg

C) 4.5  10^–27 kg

D) 6.3  10^–27 kg

E) 8.6  10^–27 kg

Difficulty: M

Section: 37-6

Learning Objective 37.6.4

68. The work that must be done to increase the speed of an electron (m = 9.11  10^–31 kg) from 0.90c to 0.95c is:

A) 8.2  10^–13 J

B) 3.2  10^–13 J

C) 2.6  10^–13 J

D) 7.4  10^–14 J

E) 3.8  10^–15 J

Difficulty: M

Section: 37-6

Learning Objective 37.6.6

69. Two isotopes of hydrogen fuse to form a helium nucleus and a neutron:

²H + ³H → ⁴He + n

The masses are:

What is the Q value of this reaction?

A) 1.9 MeV

B) 2.5 MeV

C) 2.8 MeV

D) 17.6 MeV

E) 938 MeV

Difficulty: M

Section: 37-6

Learning Objective 37.6.7